Sounds for Better Sleep

Did you make a New Year's resolution to try to get more sleep? According to the United States Centers for Disease Control and Prevention (CDC), about one-third of US adults report that they get less than the recommended 7-9 hours of sleep per night. Sleep experts list several recommendations to help you get a better night's sleep, including limiting caffeine in the evenings, avoiding screens for one hour before bedtime, creating a wind-down routine, and optimizing your sleep environment. One part of that environment could be a sound machine. White noise, brown noise, pink noise - what is the difference, and do they actually help you sleep? Here's how noise impacts sleep and how to get more rest.

For better or worse, our brains continue to process sensory stimuli when we're asleep, meaning that our partner's snoring, dog's barking, trains or traffic, and even a dripping faucet can easily impact our sleep. These noises wake us up at night not necessarily because of the noise itself, but rather the sudden change of noise. The continuous, ambient sounds of a sound machine are often used to drown out these fluctuations and allow our brains to benefit from a more consistent sound environment.

What is the "color" of noise? Audiologist Dr. Melissa Heche said, "Sound is related to color to better describe the frequency, intensity, and variation components." She added, "In audio engineering, sound is described in a whole rainbow of colors, each with its own unique properties." White, pink, and brown noise are all types of noise with varying amounts of energy at different frequencies. Because of this, they sound different to the human ear.

"White noise contains all frequencies in equal amounts, resulting in a constant hiss or rush similar to the static on a radio (or television)," Dr. Shelby Harris, a clinical psychologist specializing in behavioral sleep medicine and director of sleep health at Sleepopolis, said. It may sound like the continuous hum of a fan, a hair dryer or a vacuum. White noise is often recommended to help infants sleep better throughout the night.

Brown noise, sometimes called red noise, is more intense at lower frequencies, which produces a deep, rumbling sound; think more bass and less static than white noise. It may sound like heavy rainfall or wind, waves crashing on the shore, or the low roar of an airplane engine. Brown noise tends to have more natural variation than the other types. A 2017 study reported that employees in their workplace felt that their capabilities to concentrate and perform tasks improved while listening to brown noise through earphones.

Pink noise is a mix of white noise and brown noise. It has a lower pitch than white noise, but it does not have the deep roaring sound of brown noise. Pink noise is often described as softer, quieter, and more flat. Dr. Harris noted that pink noise can sound like gentle rain or a waterfall. Several studies on pink noise have shown that sleeping with it can improve memories the following day, and potentially even long-term.

Research on the impact of these different noises on sleep is mixed. While white noise has been studied the most, a recent analysis suggested that the quality of the evidence to support white noise as a sleep aid was poor and more research is needed.

It is generally safe to listen to these sounds for a prolonged period of time, as long as the volume doesn't reach levels that can harm the ears, which the CDC says is anything over 70 decibels. (For reference, the hum of a dishwasher is about 60 decibels.)

The color of noise that is best for sleep depends on the individual and their preferences. There are a growing number of sound machines and apps designed to play different noises. White, pink, or brown noise can also be used with other relaxation techniques, such as deep breathing or meditation.